Re: [PATCH v10 0/4] BPF controlled io_uring

[Pavel Begunkov <asml.silence@gmail.com>]

On 2/26/26 12:48, Pavel Begunkov wrote:
> Introduces a way to override the standard io_uring_enter syscall
> execution with an extendible event loop, which can be controlled
> by BPF via new io_uring struct_ops or from within the kernel.
> 
> There are multiple use cases I want to cover with this:
> 
> - Syscall avoidance. Instead of returning to the userspace for
>    CQE processing, a part of the logic can be moved into BPF to
>    avoid excessive number of syscalls.
> 
> - Access to in-kernel io_uring resources. For example, there are
>    registered buffers that can't be directly accessed by the userspace,
>    however we can give BPF the ability to peek at them. It can be used
>    to take a look at in-buffer app level headers to decide what to do
>    with data next and issuing IO using it.
> 
> - Smarter request ordering and linking. Request links are pretty
>    limited and inflexible as they can't pass information from one
>    request to another. With BPF we can peek at CQEs and memory and
>    compile a subsequent request.
> 
> - Feature semi-deprecation. It can be used to simplify handling
>    of deprecated features by moving it into the callback out core
>    io_uring. For example, it should be trivial to simulate
>    IOSQE_IO_DRAIN. Another target could be request linking logic.
> 
> - It can serve as a base for custom algorithms and fine tuning.
>    Often, it'd be impractical to introduce a generic feature because
>    it's either niche or requires a lot of configuration. For example,
>    there is support min-wait, however BPF can help to further fine tune
>    it by doing it in multiple steps with different number of CQEs /
>    timeouts. Another feature people were asking about is allowing
>    to over queue SQEs but make the kernel to maintain a given QD.
> 
> - Smarter polling. Napi polling is performed only once per syscall
>    and then it switches to waiting. We can do smarter and intermix
>    polling with waiting using the hook.

Any comments for the patch set?

-- 
Pavel Begunkov